The present invention relates generally to a vehicle wheel mounting unit. More specifically, it relates to a hub/bearing/knuckle unit wherein the bearing setting is established as the hub/bearing/knuckle unit is assembled.
Wheels are typically supported on two rows of rolling element bearings having opposing angular contact races to best support the moments placed on them in cornering. The axial relationship between these two races has often been set with a dimensional interference between the two rows so that the rolling elements have load even when no external loads are applied. This is typically referred to as preload. Normally, the wheel is attached to a hub on which the bearing inner races are located. A suspension component that attaches to control arms, springs and steering linkage, typically called a knuckle, is the support for the bearing and wheel.
Examples of bearing arrangements and setting methods are:
1xe2x80x94Outer races are pressed in a hub and a nut acting against the non-rotating inner races is used for adjustment. This is typical for medium and heavy trucks.
2xe2x80x94A unitized bearing having a pre-established setting is pressed into a knuckle and a nut is tightened to clamp the inner races of the hub/bearing assembly. The pre-established setting must accommodate the press fit.
3xe2x80x94A unitized bearing having a pre-established setting is bolted to the knuckle. The main difficulty with the first method is that the bearings can, and in fact must, be adjusted and sometimes this adjustment is poorly done by inexperienced people. It is extremely difficult to maintain accurate bearing setting using the second method due to dimensional changes as the bearing is pressed into the knuckle. The third arrangement has good control of bearing setting, but has the disadvantage of additional weight of two structures at the outer races as well as in the knuckle that each has to be strong enough to withstand the applied loads. There is also an increase in deflections due to load concentrations in the bolted area. The third arrangement also has the disadvantage of extra interface surfaces including the bolt and bolt holes which add to the cost of the assembly.
Other attempts at installing bearings directly into a knuckle have been made, such as those described in U.S. Pat. Nos. 6,250,814 and 6,212,981. However, neither of these patents addresses the concern of adjusting the setting during assembly of the complete hub/bearing/knuckle unit. In each instance, bearing preload relies on tolerances determined before the bearing is installed into the knuckle and, as such, either extremely tight tolerances must be maintained to precisely hold hub runout or accumulation of tolerances prevents the hub runout from being held precisely.
U.S. Pat. No. 5,941,335 claims bearings preloaded by an adjusting mechanism that can, and must, be manually adjusted. As is the case with earlier designs, manual adjustment requires skilled mechanics and is not at all favored in vehicles produced in large quantities.
The present invention provides a method of combining a bearing, a hub and a steering knuckle as a unit having a predetermined bearing setting. The bearing includes one or more outer races having first and second outer raceways that are inclined in opposite directions with respect to an axis of rotation of the hub. First and second inner raceways are presented toward and inclined in the same directions as the first and second outer raceways, respectively. At least the second inner raceway is on an inner race having an outboard extension and is initially separate from the hub. The outboard extension contacts an abutment face that is along the hub that establishes the second inner raceway""s axial position. Rolling elements are organized in a first row between the first raceways and in a second row between the second raceways. The bearing will transmit radial loads and thrust loads in both axial directions between the knuckle and the hub.
The method comprises fitting one or more outer races into the knuckle, ascertaining the axial length of the outboard extension on the initially separate inner race that will place the bearing in a predetermined condition of preload when the initially separate inner race is fitted over the hub and against the abutment face, providing and installing said initially separate inner race having the ascertained outboard extension length on the hub and against the abutment face, and clamping the initially separate inner race against the abutment face to insure that the bearing remains in preload.
In a second aspect, the invention provides a unit for mounting a road wheel to an automotive vehicle. The unit comprises a knuckle, a hub and a bearing. The knuckle has a cavity that opens laterally out of the knuckle. The hub has an abutment face on a spindle located in the cavity of the knuckle and a flange located beyond the cavity for providing a surface along which the road wheel is secured. The bearing is located between the knuckle and the spindle of the hub for enabling the hub to rotate in the knuckle about an axis that is fixed in position with respect to knuckle. The bearing includes one or more outer races fitted into the cavity of the knuckle. The one or more outer races have first and second outer raceways that are presented inwardly toward the axis and are inclined with respect to the axis in opposite directions. A first inner raceway is carried by the hub spindle and presented outwardly toward and inclined in the same direction as the first outer raceway. An initially separate inner race has a second inner raceway that is presented outwardly toward and inclined in the same direction as the second outer raceway. The initially separate inner race has an outboard extension. First rolling elements are organized in a first row to operate between the first raceways, and second rolling element organized in a second row to operate between the second raceways. The length of the outboard extension has been ascertained after the one or more outer races have been installed in the knuckle such that when the outboard extension contacts the abutment face the bearing operates in preload. Finally, the inner races and rolling elements having been installed in the knuckle cavity with the outboard extension clamped against the abutment face preventing the initially separate inner race from moving away from the abutment face.